# define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int i, j;
	double sum1=0, sum2=0;
	for (i = 1; i <= 100; i += 2)
	{
		sum1 = sum1 + (1.0) / i;
	}
	for (j = 2; j <= 100; j += 2)
	{
		sum2 = sum2 + (1.0) / j;
	}
	printf("%f", sum1 - sum2);
	return 0;
}
